Enhanced adsorption of aqueous copper(II) ions using dedoped poly-N-phenylglycine nanofibers

• Poly-N-phenylglycine nanofibers (PPG NFs) were synthesized simply by radical polymerization process.
• High-density functional groups of PPG NFs were exploited for adsorption of aqueous Cu.
• Simple deprotonation process enhanced the Cu adsorption capability of PPG NFs.
• The higher adsorption capacity was found under high pH conditions, owing to spontaneous deprotonation of PPG NFs.

We report on adsorption of aqueous Cu2+ using poly N-phenylglycine (PPG) nanofibers (NFs) prepared by radical polymerization process. The carboxylic acid groups of pristine PPG NFs were deprotonated to form carboxylate groups, resulting in hydrogen-dedoped PPG NFs. The Cu2+-adsorption capability of PPG NFs was markedly increased after the deprotonation, presumably due to high ionic attraction feature of carboxylate in dedoped PPG. We further investigated the pH-dependent adsorption capability of PPG NFs and found much higher Cu2+ adsorption capacity under high pH conditions, owing to spontaneous deprotonation by the basic solution. X-ray photoemission confirmed the adsorption of Cu2+ on PPG NFs, and Fourier transform infrared spectroscopic analyses confirmed the reduced density of carboxylic acid by deprotonation. The ability of pristine and dedoped PPG NFs to capture aqueous Cu2+ is discussed. Our method to improve the adsorption capability using surface modification could be readily applied to many other polymeric or organic nanostructures for metal removal.

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